Audio app note from Diodes Incorporated about the tiny PAM8908 audio line driver that streamlines driving a small load speakers in single rail power supply. Link here (PDF)
The DIODES™ PAM8908 stereo headphone driver is designed for portable equipment where board space is at a premium. The PAM8908 uses a patented unique architecture to produce a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving cost, board space, and component height.
The PAM8908 delivers up to 25mW per channel into a 16Ω load and has low 0.03% THD+N.
A high power-supply rejection ratio allows this device to operate from noisy digital supplies without an additional linear regulator.
The PAM8908 operates from a single supply from 2.5V to 5.5V, has short-circuit and overtemperature protection. Shutdown mode reduces supply current to less than 1μA.